From the Guidelines
The hydrogen breath test is used to diagnose certain digestive disorders, primarily lactose intolerance, small intestinal bacterial overgrowth (SIBO), and carbohydrate malabsorption conditions. The test works by measuring the amount of hydrogen gas in a person's breath after they consume a specific sugar solution (typically lactose, glucose, fructose, or lactulose) 1. When these sugars aren't properly absorbed in the small intestine, they reach the colon where bacteria ferment them, producing hydrogen gas that is absorbed into the bloodstream and eventually exhaled.
Key Points to Consider
- The test is non-invasive and relatively simple, though patients must follow dietary restrictions before testing, including fasting and avoiding certain foods and medications that could affect results 1.
- Elevated hydrogen levels compared to baseline indicate malabsorption or bacterial overgrowth.
- However, the sensitivity and specificity of hydrogen breath tests have been found to be low, with studies showing poor results for glucose and lactulose-hydrogen breath tests 1.
- The British Society of Gastroenterology recommends against using hydrogen breath tests for the diagnosis of small bowel bacterial overgrowth due to their poor sensitivity and specificity 1.
- The test helps clinicians determine appropriate treatment plans for digestive symptoms like bloating, gas, diarrhea, and abdominal pain.
Important Considerations
- Patients with very low 75SeHCAT values are most likely to have a response to treatment with bile acid sequestrants 1.
- Colonic biopsies to exclude microscopic colitis are recommended, with biopsies taken from the left side and potentially the right side to improve diagnostic yield 1.
- The utility of concurrent hydrogen and methane breath testing with measurements of orocaecal transit time could reduce a false positive diagnosis due to variability in intestinal transit, but has not been subject to definitive clinical study 1.
From the Research
Hydrogen Breath Test Uses
The hydrogen breath test is used for various purposes, including:
- Diagnosing small intestinal bacterial overgrowth (SIBO) 2
- Detecting specific sugar malabsorption, such as lactose, fructose, and sorbitol malabsorption 2, 3, 4, 5, 6
- Evaluating carbohydrate intolerance in patients with chronic abdominal pain 4
- Distinguishing between SIBO and carbohydrate intolerance 5
- Assessing the effectiveness of dietary interventions in patients with fructose and lactose intolerance 6
Specific Applications
- Lactose intolerance diagnosis: The hydrogen breath test is a non-invasive, inexpensive, and highly sensitive and specific method for diagnosing lactose intolerance 3
- Fructose malabsorption diagnosis: The test is used to detect fructose malabsorption, which can cause symptoms such as abdominal pain, bloating, and gas 4, 5, 6
- SIBO diagnosis: The lactulose hydrogen breath test is a reliable and non-invasive test for diagnosing SIBO 2